How to project an image, and bake it so to speak, on an angled plane
You can use the "Project from view" option from the unwrap menu. That will project the uvs of your object to match the dimensions of your camera.
Create a plane an subdivide it a number of times. Place a camera so that it faces the plane at an angle and there is no empty space within the render frame.



Remember to set your render dimensions to the same ones of your reference image. Example 350 * 350 



While in edit mode, press  u or click on "UV" on the topbar and choose "Project from view".

Create a new material and assign it to your plane. Now add an "Image texture" node and plug it into the color of your shader. Select your image. Set it to "Clip" so that it doesn't repeat outside the camera view.



Result from the camera view Numpad 0:



And from top view Numpad 7 :